Crazy problem: controllers don't load

[eluser]swissbastian[/eluser]
Hi there

I've got a very strange problem. Have updated CI to version 1.6.2. Worked all fine. Now the page doesn't load the controllers. I always get the index page, means CI always loads the index controller and the index function there. If I change the index controller in routes.php to any other controller, the page is reloads itself all the time without displaying anything.

I can't remember to have changed anything on my application. What should I do now? :-(